This application is the U.S. national stage of Patent Cooperation Treaty application number PCT/NO 00/00044 filed Feb. 8, 2000, and claims the benefit of priority to Norwegian application 19990781, filed Feb. 19, 1999.
Not Applicable.
Not Applicable.
This invention relates to a device for annular isolation in an oil/gas well comprising a casing.
Zone isolation in oil production is especially important in horizontal open hole wells in which the well penetrates a number of formations, which may require simultaneously controlling sand using screens. In controlling water or gas migrations in these formations it is important for maximizing the well""s potential and lifetime to secure annular isolation in these zones. This has been done using so-called ECP""s (External Casing Packers) in which, after packing elements have been positioned in the well, a tool is lowered which inflates a rubber bellows with concrete. This operation has been performed in a number of wells with variable results.
In the patent publications U.S. Pat. No. 3,581,816 and NO 172.554, inflatable packers are described for positioning in casings and sealing at a chosen position in the well. In practice these solutions have not functioned satisfactory.
It is an object of this invention to provide a device for annular isolation in wells which may be mounted integral with the wells casing, and which may be activated at a chosen position in the well to hinder movement of gas or liquids along the well.
Several solutions have been suggested for sealing or anchoring of packer devices in casings or similar, as is shown in the following patent publications: GB 1.245.383, GB 2.074.635, U.S. Pat. No. 3,561,529, U.S. Pat. No. 4,548,265 and U.S. Pat. No. 4,554,973. However, none of these solutions are] suitable for use in long horizontal sections. Also, these solutions have limitations in the available amount of expansion, which follows from the fact that they are adapted to be used in casings having known dimensions. A device for obtaining annular isolation in a well also has to provide sealing against the formation the cases in which the well is oval or has other deviations from a circular cross section.
It is thus an object of the present invention to provide a device for annular well isolation able to make a seal against the formation in a well when the well has a non-circular cross section.
To obtain these objects, a device as described above is, according the invention, provided which in the production pipe comprises a coaxially positioned cylindrical sealing crown coupled to a release mechanism adapted to push the sealing crown out through the opening, the sealing crown being expandable in the tangential direction.
In this way, an annular packer is obtained which may be integrated in a chosen position in a casing during installation, and which may be activated using available tools to engage the surrounding formations with varying quality and with varying cross sections. The installed packer constitutes a part of the casing and, thus does not hinder the normal use of the well.